Referring to FIG. 1A. A helical coil spring type seal is made by welding individual C-shaped rings together to form a coiled structure. The flat surface of each ring is placed in close contact with the flat surface of the adjacent ring. In one embodiment, the C-shaped rings are cut from metal sheet, welded and stacked together to form the layers in a helical coil structure. This will make sure that the cross section of each layer is always in rectangle shape. The flat surfaces of the layers will be in full contact with each other to prevent leaks between the layers and enable the sealing function. The layers of coil are then grinded to have different diameters corresponding to the different sealing surfaces.
However, referring to FIG. 1B, when a coil structure is made by welding the C-rings together, in many cases, it is essential that all the layers are sharing the same center when all the C-rings have been welded separately, especially when they have different diameters that some of them seal the shaft surface, some of them seal the cylinder surface, and some of them neither be in contact with the shaft nor the cylinder.
One difficulty arises during the making of a helical coil spring type seal is to make the stacked layers of ring sharing the same center point when each layer is made from welding the C-shaped rings together end to end and one by one individually. The difficulty escalates when the stacked layers of ring are to be made having different diameters.
Consequently, there is an unmet need to have a method and/or apparatus for fabricating a helical coil spring type seal, in which all the C-shaped rings that have welded together share the same center lying on the same center line.